/**
 * Software License, Version 1.0
 * 
 * Copyright 2003 The Trustees of Indiana University.  All rights reserved.
 * 
 *
 *Redistribution and use in source and binary forms, with or without 
 *modification, are permitted provided that the following conditions are met:
 *
 *1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license;
 *2) All redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the disclaimer listed in this license in
 * the documentation and/or other materials provided with the distribution;
 *3) Any documentation included with all redistributions must include the 
 * following acknowledgement:
 *
 *"This product includes software developed by the Community Grids Lab. For 
 * further information contact the Community Grids Lab at 
 * http://communitygrids.iu.edu/."
 *
 * Alternatively, this acknowledgement may appear in the software itself, and 
 * wherever such third-party acknowledgments normally appear.
 * 
 *4) The name Indiana University or Community Grids Lab or NaradaBrokering, 
 * shall not be used to endorse or promote products derived from this software 
 * without prior written permission from Indiana University.  For written 
 * permission, please contact the Advanced Research and Technology Institute 
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202.
 *5) Products derived from this software may not be called NaradaBrokering, 
 * nor may Indiana University or Community Grids Lab or NaradaBrokering appear
 * in their name, without prior written permission of ARTI.
 * 
 *
 * Indiana University provides no reassurances that the source code provided 
 * does not infringe the patent or any other intellectual property rights of 
 * any other entity.  Indiana University disclaims any liability to any 
 * recipient for claims brought by any other entity based on infringement of 
 * intellectual property rights or otherwise.  
 *
 *LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO 
 *WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 *NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF 
 *INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS. 
 *INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS", 
 *"VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.  
 *LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR 
 *ASSOCIATED MATERIALS, AND TO THE PERFORMANCE AND VALIDITY OF INFORMATION 
 *GENERATED USING SOFTWARE.
 */
package cgl.narada.transport.util;


import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;

import cgl.narada.util.ByteUtilities;


public class MulticastAcceptor extends Thread {

    private InetAddress group;
    private int port;
    private MulticastSocket msock;
    private int bufLen = 1024;

    public MulticastAcceptor(int port) {
	try {
	    this.port = port;
	    this.msock = new MulticastSocket(this.port);
	    this.group = InetAddress.getByName("224.224.224.224");
	    this.msock.joinGroup(group);	
	} catch (Exception e) {
	    e.printStackTrace();
	    System.err.println("MulticastAcceptor initialization problem at port "+port+", exit");
	    System.exit(0);	
	}   
    }

    public static void main(String[] args) {
	int port = 4045;
	if (args.length == 1) port = Integer.parseInt(args[0]);
	MulticastAcceptor acceptor = null;
	try {
	    acceptor = new MulticastAcceptor(port);
	    acceptor.setDaemon(true);
	    acceptor.start();
	    
	    while(true) {
		try {
		    Thread.sleep(5*1000);
		} catch (Exception e) {
		    continue;
		}
	    }

	} catch (Exception e) {
	    e.printStackTrace();
	}
	finally {
	    if (acceptor != null) acceptor.leaveGroup();
	}

    }

    public void run() {
	while (true) {
	    try {
		byte[] buf = new byte[bufLen];
		DatagramPacket recv = new DatagramPacket(buf, buf.length);
		msock.receive(recv);
		String incomingIP = InetAddress.getLocalHost().getHostAddress();
		System.out.println("Incoming IP="+incomingIP);
		if (! recv.getAddress().getHostAddress().equals(incomingIP)){
		    byte[] data = recv.getData();
		    int len = recv.getLength();
		    int challenge = ByteUtilities.getInt(data);
		    System.out.println("Receive challenge "+challenge);
		    int response = challenge+1;
		    byte[] responseBytes = ByteUtilities.getBytes(response);
		    DatagramPacket dpack = 
			new DatagramPacket(responseBytes, responseBytes.length, this.group, this.port);
		    msock.send(dpack);
		} else {
		    System.out.println("Self's message received");
		}

	    } catch (Exception e) {
		e.printStackTrace();
	    }  finally {
		try {
		    Thread.sleep(1000);
		} catch (Exception e) {
		    continue;
		}
	    }
	}
    }

    public void leaveGroup() {
	try {
	    this.msock.leaveGroup(this.group);
	} catch (Exception e) {
	    e.printStackTrace();
	}
    }

}
